Cole Kan/ZDNET/Apple/Oura/Sony/Samsung/Amazon Follow ZDNET: Add us as a preferred source on Google. With Amazon's October Prime Day coming up this week, deals and discounts are top of mind. It can be overwhelming to sift through all the deals to see what's worth the discount, but luckily, ZDNET has years of experience finding the best sales that are actually worth your money. Also: The best October Prime Day deals live now To help you shop more efficiently during Amazon Prime Day (Oct. 7-8), we broke down how to spot a good deal based on a product's price history and what to look for. We looked at the top ZDNET products (based on our best list picks and what readers are searching for and buying) to come up with our list of products to compare prices. Here are the products we chose and their current prices at the time of publication: We also chose a handful of budget products (priced at $200 or less) to showcase the difference of discounts with cheaper devices. How we compared deal prices Using the Camel Camel Camel Google Chrome plugin, we were able to see a product's pricing over time using the deal-tracking system's advanced algorithm. We chose the parameters of lowest price, highest price, and average price so that readers can clearly see the difference in prices. Also: Shopping this October Prime Day? Here's how to use Amazon's tools to find the best deals The lowest price is the lowest sale price that was recorded, while the highest price is the highest price that was recorded on a site. (Since Amazon Prime Day is coming up, we chose Amazon as our main reference site.) Keep in mind that the highest price is almost always the MSRP price. The average price is calculated by combining the prices for that product over a period of time. It's important to note that the current price of the product is not always the highest price or the average price. We then created an interactive visualization to showcase these price differences using color coding (green for the lowest price, fuchsia for the highest price, and blue for the average price) for each product we chose to compare. To keep in mind what is a good deal, this is the deal-rating system we use at ZDNET: 1-9% off : 1 / 5 Editor's deal rating : 1 / 5 Editor's deal rating 10-19% off : 2 / 5 Editor's deal rating : 2 / 5 Editor's deal rating 20-29% off : 3 / 5 Editor's deal rating : 3 / 5 Editor's deal rating 30-39% off : 4 / 5 Editor's deal rating : 4 / 5 Editor's deal rating 40-50% (or more) off: 5 / 5 Editor's deal rating Overall, a 3/5 and up deal rating is a deal we think is worth buying. However, deals of less than 20% off can be great buys on a case-by-case basis, especially for products that don't frequently see sales -- like new Apple products. Which deals are worth it To see which deals are worth it, it's best to look at the lowest price and highest price comparisons to know if you're getting a good discount. As you can see from our top products visualization chart (Figure 1), the iRobot Roomba j7+ had the greatest difference in price between its lowest price and highest price ($350 vs. $850). Both of our top TV picks also had big differences in pricing, which is the trend we usually find with most TVs, making a TV deal something to look out for. On the other hand, the Sony WH-1000XM6 and the Oura Ring Gen 4 had the lowest difference in lowest in average prices, at a $22 difference (5% off) and a $74 difference (15% off), respectively. This means that the past deals on these products are not good. It also means if you see more of a discount on these prices on these two products during Prime Day, snag it, because that would be the best deal these products have had yet to date. However, the budget products visualization (Figure 2) was a little different than our top products one. Since they are overall priced much less, their discounts and differences in pricing will be much less as well. We see the lowest price ranging from only $5-$78 off the highest pricing. Also: The best Amazon Prime Day deals under $100 The budget products that saw the highest discounts were the Beats Studio Buds at a $78 difference (52% off) and the Blink Outdoor 4 camera at a $75 difference (68% off), meaning these products are considered good deals. Other budget products, though, like the Torras MiniMag Power Bank ($5 difference) and the base Amazon Kindle ($20 difference), offered small discounts at 10% off and 18% off ranges, making these not-so-good deals, but still affordable buys for their lower price tags. Of course, we aren't saying not to buy something if the deal isn't great, but just keep in mind this Prime Day that not every deal is worth buying. When is the best time to save on tech? Sales events like Prime Day, Black Friday, and Cyber Monday are by far the best ways to save on tech, especially big brands like Apple, Samsung, and LG. Also: Everything you need to know about October Prime Day This year, October Prime Day sales happen Oct. 7-8. Black Friday will be on Friday, Nov. 28, and Cyber Monday falls on Dec. 1. Show more How do we rate deals at ZDNET? ZDNET only writes about deals we want to buy -- devices and products we desire, need, or would recommend. Our experts looked for deals that were at least 20% off (or are hardly ever on sale), using established price comparison tools and trackers to determine whether the deal is actually on sale and how frequently it drops. We also looked over customer reviews to find out what matters to real people who already own and use the deals we're recommending. Our recommendations may also be based on our own testing -- in addition to extensive research and comparison shopping. The goal is to deliver the most accurate advice to help you shop smarter. Show more